[Serusers] dispatcher addition?

[Hendrik Scholz]

Hi!

Andrei Pelinescu-Onciul wrote:
> Balance the REGISTERs after the to uri and the INVITEs after the request
> uris (ds_select_dst("..", "3"), not documented but present in unstable).

I already found those when backporting the dispatcher module to 0.8.14.

> If the uri is an alias (e.g. lookup("aliases") returns true) balance the
> message again after the request uri/send it back to the load balancer.

Let's pretend this:
I register UA 'a' and it get's balanced to SER backend 'Y'.
I register UA 'b' and it get's balanced to SER backend 'Z'.

Now 'a' also has an alias (a phone number) of '123456'.

If I call 'a' the load balancer takes care of everything and backend 'Y'
can process the call.
Now '123456' get's balanced to 'Z' due to the hash algorithm.
Since the initial register of 'a' was on 'Y' the 'Z' backend doesn't
know anything about the alias.
Or am I getting something wrong here?

My idea was to get the alias from Radius instead of the incomplete
usrloc DB. The additional hop involved is needed to push the
request to the backend ('Y') where 'a' initially registered on.

> An extra round trip might be involved, but if your users don't use
> aliases very often it might not be an issue.

We do have many aliases and all calls from the PSTN have to be
looked up but I think it's easier to do the lookup on the backend
rather than having a usrloc DB on the load balancer.

Hendrik

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